This Shocking Acetaminophen Side Effect May Have You Rethinking Your Pain Reliever Choice

Like many people, I often find myself reaching for acetaminophen to deal with a headache, backache, or other minor aches and pains. So, I was surprised to hear about a new study claiming acetaminophen has a previously unknown side effect: it blunts positive emotions as well as feelings of physical pain.

Acetaminophen is the main ingredient in the over-the-counter pain reliever Tylenol. It is the most common drug in the US and can be found in over 600 different medications. However, this is the first time that this side effect has been documented even though acetaminophen has been in use for over 70 years.

In the study, participants who took acetaminophen reported less intense emotions when they saw both very pleasant and very disturbing photos as compared to people taking only a placebo. The photographs were chosen to elicit extremely unpleasant (crying, malnourished children), neutral (a cow in a field), or very pleasant (young children playing with cats) responses. Participants taking acetaminophen reacted to both positive and negative images with less intensity than those taking a placebo, although acetaminophen didn’t change their reaction to the neutral images.

“This means that using Tylenol or similar products might have broader consequences than previously thought,” said Geoffrey Durso, lead author of the study and a doctoral student in social psychology at The Ohio State University. “Rather than just being a pain reliever, acetaminophen can be seen as an all-purpose emotion reliever.”

People in the study who took the pain reliever didn’t appear to know they were reacting differently, so you can’t assume that you’d realize if you were experiencing negative effects from your Tylenol. However, if you’re bothered by the prospect of blunting perceptions of both pain and pleasure, it’s certainly worth asking your physician to recommend an alternative pain reliever.